Spontaneous Bacterial Peritonitis in Advanced Cirrhosis: Diagnosis by Tm Mapping and Inflammatory Profiles of Extracellular Vesicles.

Background/

Objectives

Ascites is a major complication in patients with decompensated cirrhosis. Spontaneous bacterial peritonitis (SBP), an infection of the ascitic fluid, is a life-threatening condition in patients with cirrhosis. This study aimed to assess the utility of Tm mapping, a novel high-efficacy method for bacterial detection and quantification, in the early diagnosis of SBP and its pathogenesis.

Methods

Ascitic fluid samples from 29 patients with cirrhosis were analyzed using Tm mapping for bacterial identification. Inflammatory cytokine and pathogen-associated molecular pattern levels in ascitic fluid were measured and correlated with SBP pathophysiology. Additionally, the role of ascitic macrophages was investigated in vitro.

Results

Tm mapping detected bacteria more effectively than conventional culture methods. In samples where bacteria were identified, ascitic interleukin (IL)-6 levels were elevated. A positive correlation was observed between extracellular vesicle (EV) levels and IL-6, suggesting a role for EVs in peritoneal inflammation. Furthermore, EVs derived from Gram-negative bacteria induced M1 macrophage differentiation via the signal transducer and activator of transcription 1 signaling pathway.

Conclusions

Tm mapping is a valuable tool for the early detection of bacteria in ascitic fluid. Additionally, EVs promote M1 macrophage differentiation, implicating them in the pathogenesis of cirrhotic complications, including SBP.